... Their study indicates that the Sepi-olidae is both widely distributed and speciose in Austral... more ... Their study indicates that the Sepi-olidae is both widely distributed and speciose in Australian waters (Lu and Okutani, in preparation). ... 1). Number of speci-mens is indicated, followed by the mantle length or range in mantle length (ML) in mm. ...
The captures of pelagic ce phalo pods by th e 3 m Isaacs-Kidd midwater trawl (IKMT), the 8m 2 ree... more The captures of pelagic ce phalo pods by th e 3 m Isaacs-Kidd midwater trawl (IKMT), the 8m 2 reetangular midwater trawl (RMT 8) , and the small (1400 mesh) Engeltrawl (E. MT) are compared. The sampling site was a o ne-d egree square area in the North Atlantic O cean east of Bt;rmuda kno wn as O cean Acre. The IKMT and the RMT 8 were equipped with closing devices. Comparative samples we re ta ke n o n the same ct•uise or at least during the same season of the year. The compa riso ns we re made on net captures ta ken at J< l standardized depth increme nts fro m th e surface to 1250 m fo r both daytime and night-time. Co mparisons were developed for catch rate (standardized to number of specime ns ca ptured per hour of trawling) , species co mpos ition , size distribution, and co-occurrence of species. The co mpariso n of IKMT and the RMT 8, nets with nearl y equiva le nt m o uth o pe nings , indicates that the IKMT catches slightl y larger specimens of the same species than the RMT 8. The RMT 8, ho weve r , ca tches mo re specimens per ho ur of a give n species than the IKMT, and it te nds to catch a greater d ive rsity of species. The Engel trawl. . a ne t with a mu ch larger area of mouth ope ning th an the o ther nets, catches a significantly grea ter numbe r o f species, more specime ns o f eac h species, and very much !arger specimens than eithe r the IKMT or the RMT 8.
A behavior that has never been seen in cephalopods was observed three times in a large aggregatio... more A behavior that has never been seen in cephalopods was observed three times in a large aggregation of Brachioteuthis beanii Verrill, 1881. During a series of submersible dives off Cape Hatteras, North Carolina, eastern U. S., three pairs of Brachioteuthis were seen, and one pair was video-taped. In all three pairs one squid grasped the other by the posterior mantle in its arm crown. This paired behavior involved brief periods in which the grasped squid bent its head and body posteriorly and vigorously moved its arms around the head and mantle opening of the grasping squid. Although we were unable to capture any of the coupling pairs to determine their stage of maturity, we believe this unusual activity represents mating behavior.
Order Teuthoidea (Cephalopoda) SMITHSONIAN INSTITUTION PRESS CITY OF WASHINGTON 1969 SERIAL PUBLI... more Order Teuthoidea (Cephalopoda) SMITHSONIAN INSTITUTION PRESS CITY OF WASHINGTON 1969 SERIAL PUBLICATIONS OF THE SMITHSONIAN INSTITUTION The emphasis upon publications as a means of diffusing knowledge was expressed by the first Secretary of the Smithsonian Institution. In his formal plan for the Institution, Joseph Henry articulated a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge not strictly professional." This keynote of basic research has been adhered to over the years in the issuance of thousands of titles in serial publications under the Smithsonian imprint, commencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series:
Several tissues (e.g. kidney, blood, digestive gland) in oceanic cephalopods which do not exhibit... more Several tissues (e.g. kidney, blood, digestive gland) in oceanic cephalopods which do not exhibit in vivo bioluminescence, luminesce when homogenized in the presence of air or when simply exposed to air in a vial (blood). The source of the luminescence appears to be a luciferin: treatment of kidney homogenates and blood with a photophore extract presumably containing luciferase resulted in a 20-fold increase in light production. Luminescence was also found in the renal fluid, which may be the source of luminescent clouds produced by squids. The variability in luminescence found in some tissues of cephalopods appeared to be related to feeding. Luminescence was also detected in the digestive glands of midwater octopods.
The means of detecting downwelling light for counterillumination in several midwater animals has ... more The means of detecting downwelling light for counterillumination in several midwater animals has been examined. Eyes and extraocular photoreceptors (dorsal photosensitive vesicles in the enoploteuthid squid Abraliopsis sp. B and pineal organs in the myctophid fish Mgctophum spinosum) were alternately exposed to overhead light or covered by a small opaque shield above the animal and the bioluminescent response of the animal was monitored. Covering either the eyes or the extraocular photoreceptors resulted in a reduction in the intensity of counterillumination. Preliminary experiments examining the bioluminescent feedback mechanism for monitoring intensity of bioluminescence during counterillumination in the midwater squid Abralia trigonura indicated that the ventral photosensitive vesicles are responsible for bioluminescent feedback.
... Their study indicates that the Sepi-olidae is both widely distributed and speciose in Austral... more ... Their study indicates that the Sepi-olidae is both widely distributed and speciose in Australian waters (Lu and Okutani, in preparation). ... 1). Number of speci-mens is indicated, followed by the mantle length or range in mantle length (ML) in mm. ...
The captures of pelagic ce phalo pods by th e 3 m Isaacs-Kidd midwater trawl (IKMT), the 8m 2 ree... more The captures of pelagic ce phalo pods by th e 3 m Isaacs-Kidd midwater trawl (IKMT), the 8m 2 reetangular midwater trawl (RMT 8) , and the small (1400 mesh) Engeltrawl (E. MT) are compared. The sampling site was a o ne-d egree square area in the North Atlantic O cean east of Bt;rmuda kno wn as O cean Acre. The IKMT and the RMT 8 were equipped with closing devices. Comparative samples we re ta ke n o n the same ct•uise or at least during the same season of the year. The compa riso ns we re made on net captures ta ken at J< l standardized depth increme nts fro m th e surface to 1250 m fo r both daytime and night-time. Co mparisons were developed for catch rate (standardized to number of specime ns ca ptured per hour of trawling) , species co mpos ition , size distribution, and co-occurrence of species. The co mpariso n of IKMT and the RMT 8, nets with nearl y equiva le nt m o uth o pe nings , indicates that the IKMT catches slightl y larger specimens of the same species than the RMT 8. The RMT 8, ho weve r , ca tches mo re specimens per ho ur of a give n species than the IKMT, and it te nds to catch a greater d ive rsity of species. The Engel trawl. . a ne t with a mu ch larger area of mouth ope ning th an the o ther nets, catches a significantly grea ter numbe r o f species, more specime ns o f eac h species, and very much !arger specimens than eithe r the IKMT or the RMT 8.
A behavior that has never been seen in cephalopods was observed three times in a large aggregatio... more A behavior that has never been seen in cephalopods was observed three times in a large aggregation of Brachioteuthis beanii Verrill, 1881. During a series of submersible dives off Cape Hatteras, North Carolina, eastern U. S., three pairs of Brachioteuthis were seen, and one pair was video-taped. In all three pairs one squid grasped the other by the posterior mantle in its arm crown. This paired behavior involved brief periods in which the grasped squid bent its head and body posteriorly and vigorously moved its arms around the head and mantle opening of the grasping squid. Although we were unable to capture any of the coupling pairs to determine their stage of maturity, we believe this unusual activity represents mating behavior.
Order Teuthoidea (Cephalopoda) SMITHSONIAN INSTITUTION PRESS CITY OF WASHINGTON 1969 SERIAL PUBLI... more Order Teuthoidea (Cephalopoda) SMITHSONIAN INSTITUTION PRESS CITY OF WASHINGTON 1969 SERIAL PUBLICATIONS OF THE SMITHSONIAN INSTITUTION The emphasis upon publications as a means of diffusing knowledge was expressed by the first Secretary of the Smithsonian Institution. In his formal plan for the Institution, Joseph Henry articulated a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge not strictly professional." This keynote of basic research has been adhered to over the years in the issuance of thousands of titles in serial publications under the Smithsonian imprint, commencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series:
Several tissues (e.g. kidney, blood, digestive gland) in oceanic cephalopods which do not exhibit... more Several tissues (e.g. kidney, blood, digestive gland) in oceanic cephalopods which do not exhibit in vivo bioluminescence, luminesce when homogenized in the presence of air or when simply exposed to air in a vial (blood). The source of the luminescence appears to be a luciferin: treatment of kidney homogenates and blood with a photophore extract presumably containing luciferase resulted in a 20-fold increase in light production. Luminescence was also found in the renal fluid, which may be the source of luminescent clouds produced by squids. The variability in luminescence found in some tissues of cephalopods appeared to be related to feeding. Luminescence was also detected in the digestive glands of midwater octopods.
The means of detecting downwelling light for counterillumination in several midwater animals has ... more The means of detecting downwelling light for counterillumination in several midwater animals has been examined. Eyes and extraocular photoreceptors (dorsal photosensitive vesicles in the enoploteuthid squid Abraliopsis sp. B and pineal organs in the myctophid fish Mgctophum spinosum) were alternately exposed to overhead light or covered by a small opaque shield above the animal and the bioluminescent response of the animal was monitored. Covering either the eyes or the extraocular photoreceptors resulted in a reduction in the intensity of counterillumination. Preliminary experiments examining the bioluminescent feedback mechanism for monitoring intensity of bioluminescence during counterillumination in the midwater squid Abralia trigonura indicated that the ventral photosensitive vesicles are responsible for bioluminescent feedback.
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Papers by Clyde Roper